The present invention relates to a dual gate tracker and method and more specifically a dual gate tracker utilized in a guided missile control system.
Systems for tracking an object within a field of view are well known in the art. Such systems customarily employ a television camera or other means for generating an electronic signature of the object within the field of view. This electronic signature is generally differentiated to accent any change in contrast and the movement of this edge or contrast change within the field of view of the camera is utilized for tracking and/or control purposes. Such systems are known as single gate trackers and are very effective where the object tracked is quite small relative to the field of view of the camera.
Problems, however, arise when the object tracked is large for the reason that the point of contrast, i.e., the edge of the target, may be displaced a considerable distance from the center thereof due either to the physical size of the target or the proximity of the camera thereto. The signal related to target position thus generated, while not erroneous as to the edge of the target, may be entirely unsatisfactory for the desired control purpose. For example, the delivery of a missile on the extreme edge of a large target such as a tank, marine vessel, or the like, may not only allow the target to avoid destruction but escape without substantial injury.
This single edge tracking problem is more acute where, as in the case of a vessel under way, the point of contrast tracked by the apparatus may not in fact be the stern of the ship but may be the contrast of the wake of the vessel relative to the sea, resulting in the delivery of the missile into the water astern of the vessel.
It is accordingly an object of the present invention to obviate the deficiencies of these known prior art systems and to provide a novel method and apparatus for the centroid tracking of a target within a field of view.
It is another object of the present invention to provide a novel method and apparatus for tracking the center of a target by averaging the tracking signals from dual gates.
It is still another object of the present invention to provide a novel method and apparatus for dual gate tracking including means to prevent the collapsing of the dual gates into a single gate.
It is yet another object of the present invention to provide a novel method and means for controlling the flight of a guided missile.
It is yet still another object of the present invention to provide a novel method and means for tracking the opposing contrast edges of a target and for generating an error signal responsive thereto.